1. Technical Field
The present disclosure relates to radiofrequency amplifiers that use phase-shifted full bridge resonant inverters. Particularly, the present disclosure is directed to reducing the cost and complexity of the resonant inverters and improving the performance of the resonant inverters.
2. Background of the Related Art
Energy-based tissue treatment is well known in the art. Various types of energy (e.g., electrical, ultrasonic, microwave, cryogenic, thermal, laser, etc.) are applied to tissue to achieve a desired result. Electrosurgery involves application of high radio frequency electrical current to a surgical site to cut, ablate, coagulate or seal tissue. A source or active electrode delivers radio frequency energy from the electrosurgical generator to the tissue and a return electrode carries the current back to the generator. In monopolar electrosurgery, the source electrode is typically part of the surgical instrument held by the surgeon and applied to the tissue to be treated and the return electrode is placed remotely from the active electrode to carry the current back to the generator. In bipolar electrosurgery, one of the electrodes of the hand-held instrument functions as the active electrode and the other as the return electrode.
FIG. 1 is an example of a prior art electrosurgical generator that uses a phase-shifted full bridge resonant inverter to generate the electrosurgical energy needed to perform the electrosurgical procedure. The generator 100 includes a resonant inverter circuit 102 and a pulse width modulation (PWM) controller 108. The resonant inverter circuit 102 includes an H-bridge 104 an LCLC tank 106. However, in the electrosurgical generator 100, the transitioning of the FETs Q1, Q2, Q3, and Q4 may induce common mode currents that circulate through the resonant inverter circuit 102 causing electromagnetic compatibility (EMC) problems for the electrosurgical generator 100.